A Comparison of Head-Tracked and Vehicle-Tracked Virtual Audio Cues in an Aircraft Navigation Taask

Since the earliest conception of virtual audio displays in the 1980's, two basic principles that have guided their development have been 1) that virtual audio cues are ideal for providing information to pilots in aviation applications; and 2) that head-tracked virtual audio displays provide more accurate and more intuitive directional information than non-tracked displays. However, despite the obvious potential utility of spatial audio cues in the cockpit, very little quantitative data has been collected to evaluate the in-flight performance of pilots using virtual audio displays. In this study, sixteen pilots maneuvered a general aviation aircraft through a series of ten waypoints using only direction cues provided a virtual audio display system. Each pilot repeated the task twice: once with a virtual display slaved to the direction of the pilot's head, and once with a virtual audio display slaved to the direction of the aircraft. Both configurations provided audio cues that were sufficient for successful aircraft navigation, with pilots on average piloting their aircraft to within 0.25 miles of the desired waypoints. However performance was significantly better in the plane-slaved condition, primarily due to a leftward bias in the head-slaved flight paths. This result suggests how important frame of reference considerations can be in the design of virtual audio displays for vehicle navigation

Biofuel blending reduces particle emissions from aircraft engines at cruise conditions

Aviation-related aerosol emissions contribute to the formation of contrail cirrus clouds that can alter upper tropospheric radiation and water budgets, and therefore climate1. The magnitude of air-traffic-related aerosol–cloud interactions and the ways in which these interactions might change in the future remain uncertain. Modelling studies of the present and future effects of aviation on climate require detailed information about the number of aerosol particles emitted per kilogram of fuel burned and the microphysical properties of those aerosols that are relevant for cloud formation. However, previous observational data at cruise altitudes are sparse for engines burning conventional fuels and no data have previously been reported for biofuel use in-flight. Here we report observations from research aircraft that sampled the exhaust of engines onboard a NASA DC‐8 aircraft as they burned conventional Jet A fuel and a 50:50 (by volume) blend of Jet A fuel and a biofuel derived from Camelina oil. We show that, compared to using conventional fuels, biofuel blending reduces particle number and mass emissions immediately behind the aircraft by 50 to 70 per cent. Our observations quantify the impact of biofuel blending on aerosol emissions at cruise conditions and provide key microphysical parameters, which will be useful to assess the potential of biofuel use in aviation as a viable strategy to mitigate climate change